The invention relates to a catalyst carrier configuration, a structural unit having catalyst carrier configurations and further relates to an exhaust system of an internal combustion engine.
For catalytically converting components of an exhaust gas from an internal combustion engine, it is known to apply at least one catalytically active substance to a catalyst carrier. The catalyst carrier has gas passages through which an exhaust gas can flow. The gas passages extend in the longitudinal direction of the catalyst carrier. It is known to provide a catalyst carrier in the form of a honeycomb. The catalyst carrier may be formed from layers of sheet metal which are at least partially structured. Furthermore, catalyst carriers which are formed of a ceramic material are known. Such catalyst carriers are extruded.
The catalyst carrier is disposed in a housing which is part of an exhaust system. Various configurations of the housing are known depending on the material of the catalyst carrier.
International Patent Publication WO 90/02251 describes a housing with a catalyst carrier which is suitable in particular for installation close to the engine and within the exhaust system. The housing has a larger cross section than the catalyst carrier. The housing has an approximately rectangular opening, the length of which is greater than the maximum length of the catalyst carrier and the width of which is greater than the maximum width of the catalyst carrier. The catalyst carrier is attached to a flat or curved retention plate which has a greater length and width than the opening in the housing. The retention plate serves as a closure cover for the housing, the catalyst carrier projecting into an inner chamber in the housing. This simplifies installation of the catalyst carrier in the housing and removal of the catalyst carrier from the housing.
Further configurations of catalyst carrier configurations are known, for example, from International Patent Publications WO 96/27735, WO 96/01698 and WO 96/19647.
Particularly in the case of internal combustion engines which are installed in passenger vehicles, installing a catalyst carrier close to the engine is not without problems, since the spatial conditions inside an engine chamber of the vehicle are relatively constricted.
Published German Patent Application DE 26 35 725 A1 discloses a catalyst carrier configuration having a housing in which at least one catalyst carrier is disposed. The catalyst carrier has a plurality of passages which are separated from one another by partitions and extend in an axial direction of the catalyst carrier. The housing has a flange which is directed essentially radially outwards. The flange can be provided between a cylinder head and a manifold of an internal combustion engine. The housing is formed integrally with the flange.
Published German Patent Application DE 43 17 092 A1 discloses a catalyst carrier configuration which is disposed in the exhaust manifold of an internal combustion engine. The catalyst carrier configuration has a housing which is configured in the form of a frame. The framelike housing has collar-like beads, in order to ensure that a catalyst carrier is fixed both radially and axially in the housing. The housing is connected to a flange. The flange is welded to one of the collar-like beads. It is also known from Published German Patent Application DE 43 17 092 A1 that it is possible to connect the flange to a plurality of housings.
Published German Patent Application DE 43 22 526 A1 discloses a further configuration of a catalyst carrier configuration for an internal combustion engine. The catalyst carrier configuration has a housing in which a catalyst carrier is provided. A flange which has a collar which is fixed to the housing is connected to the housing. The flange is fixed, together with an exhaust pipe, to the cylinder head of an internal combustion engine.
It is accordingly an object of the invention to provide a catalyst carrier configuration which overcomes the abovementioned disadvantages of the heretofore-known configurations of this general type and which is of simple construction and allows installation close to an engine.
A further object of the invention is to provide a structural unit which simplifies the assembly of at least two catalyst carrier bodies in the vicinity of the internal combustion engine.
A still further object of the invention is to provide an exhaust system of an internal combustion engine which can be produced with little outlay.
With the foregoing and other objects in view there is provided, in accordance with the invention, a catalyst carrier configuration, including:
a housing having an outer wall;
at least one catalyst carrier body disposed in the housing, the at least one catalyst carrier body defining an axial direction and having partition walls defining a plurality of passages separated from one another by the partition walls and extending essentially in the axial direction; and
at least one flange surrounding at least the at least one catalyst carrier body and extending essentially radially outwards from the at least one catalyst carrier body, the at least one flange having at least one section extending at least partially into the outer wall and being configured to be disposed between a cylinder head and a manifold of an internal combustion engine.
In other words, the construction of the catalyst configuration according to the invention has a housing in which a catalyst carrier body is disposed which has a plurality of passages which are separated from one another by partition walls and extend in an axial direction of the catalyst carrier body. The housing extends at least partially in an axial direction of the catalyst carrier body. The configuration according to the invention has a housing which has at least one flange which is directed essentially radially outwards, at least partially surrounds the catalyst carrier body and can be disposed between a cylinder head and a manifold of an internal combustion engine. The flange has at least a section which projects at least partially into the housing. This construction of the catalyst configuration according to the invention forms a sharp transition between the housing and the flange, so that the catalyst carrier configuration according to the invention requires relatively little installation space. Particularly in the case of existing internal combustion engines, the problem exists that they cannot be retrofitted with catalyst carrier configurations of this type since a catalyst carrier configuration as is known, for example, from Published German Patent Application DE 43 22 526 A1 has a radius of curvature in the transition region between the exhaust manifold or the cylinder head and the housing. Such a catalyst carrier configuration can only be fitted by adapting the further components. With the catalyst carrier configuration according to the invention it is not absolutely necessary to adapt the exhaust manifold or the cylinder head in this way.
Due to the fact that the flange extends at least partially into the housing, the load on a joint between flange and housing is also relieved, since some of the forces acting on the catalyst carrier body and the housing are introduced directly into the flange via the housing. Relieving the load on the joint between the housing and the flange also has a beneficial effect on the service life and durability of the catalyst carrier configuration.
The construction of the catalyst carrier configuration according to the invention also allows retrofitting on existing internal combustion engines, with the result that emissions of certain harmful components of the exhaust gas can be reduced.
The catalyst carrier configuration preferably has dimensions which are such that the catalyst carrier body can be introduced at least partially into an outlet passage from an internal combustion engine. This configuration means that the catalyst carrier body, which is provided with a catalyst, can quickly be brought to its operating temperature, so that the emission of harmful components is reduced during a cold-start phase of an internal combustion engine, in particular a vehicle engine.
In accordance with an advantageous feature of the invention, the housing has on or in its outer wall a recess into which at least one section of the flange projects. The recess is preferably formed by a groove, in particular a continuous, encircling groove. The flange has a passage opening which preferably has an internal diameter which is greater than the external diameter of the housing. The flange is positioned in the region of the groove. Due to a radially outwardly directed deformation of the housing, at least in the region of the groove, the section of the flange passes into the recess. The plastic deformation of the housing can be achieved by placing the housing under a sufficiently high internal pressure. If appropriate, the deformation of the housing may take place at an elevated temperature.
In accordance with another feature of the invention, the recess is formed by at least one radially outwardly directed stamped or swaged section in the outer wall. The swaged or stamped section is preferably structured in the form of a bead.
In accordance with another feature of the invention, a section of the flange extends as far as the catalyst carrier body. If the catalyst carrier configuration is configured in this way, the housing is preferably of two-part construction.
In accordance with yet another feature of the invention, the housing has an extent in the axial direction of the catalyst carrier body which is smaller, preferably significantly smaller, than a length of the catalyst carrier body. As a result, the catalyst carrier configuration has a relatively low heat-storage mass, so that an operating temperature of the catalyst carrier configuration can be reached more quickly. A further advantage of this configuration is that the external dimensions of the catalyst carrier configuration can be reduced to a required level so that when the catalyst carrier configuration is disposed in an outlet from an internal combustion engine there is no need to enlarge an outlet passage. It is also achieved that the free flow cross section in the outlet passage is reduced by the catalyst carrier configuration only by an insignificant amount. Furthermore, the flow behavior of the exhaust gas is affected only insignificantly.
A housing whose extent in the axial direction of the catalyst carrier body is smaller, preferably significantly smaller, than a length of the catalyst carrier body is suitable in particular for accommodating metallic catalyst carrier bodies which are wound helically or spirally.
If it is intended, instead of a helically or spirally wound catalyst carrier body, to provide, for example, a catalyst carrier body which is wound in the form of an S in the housing, it is advantageous for the housing to be formed by at least two housing parts, each housing part extending over part of the longitudinal extent of the catalyst carrier body. This configuration of the housing has the advantage that it prevents the catalyst carrier body being spread open by the housing parts. It is not necessary for the overall length of the individual housing parts to correspond to the overall length of the catalyst carrier body. There may be free sections between individual housing parts. Given a sufficiently long housing, it is also possible for a catalyst carrier body which is wound in the form of an S to be disposed in a single-piece housing.
In accordance with yet another feature of the invention, the housing or the housing parts are provided in the form of a ring or sleeve. This configuration has the advantage that the housing or the housing parts are relatively simple to produce. The external contour of the housing or the housing parts preferably corresponds to the cross section of the outlet passage or of the exhaust-gas flow path adjoining the outlet passage.
According to a further advantageous embodiment of the invention, the flange forms a single carrying unit together with a housing or with a housing part. This has the advantage that there is no need to handle a plurality of parts.
According to a further advantageous embodiment of the carrying unit, the housing or a housing part have at least one stop which can be brought to bear against a catalyst carrier body. This allows a defined installation position of a catalyst carrier body inside the housing or the housing part.
Preferably, the catalyst carrier configuration is configured in such a way that the flange has at least one sealing surface for gastight connection to a manifold and a cylinder head. The sealing surface is preferably of annular construction, so that it surrounds the catalyst carrier body. In this case, a preferred embodiment of the catalyst configuration is one in which the flange itself forms a seal. Such a catalyst carrier configuration is suitable particularly when the catalyst carrier configuration is disposed directly on the internal combustion engine, since it is possible to dispense with additional sealing devices. Thus the flange forms a seal between an engine block and a manifold of the internal combustion engine. The proximity of the catalyst carrier configuration to the combustion chamber of an internal combustion engine ensures that the catalyst carrier body heats up relatively quickly, with the result that the catalyst carrier configuration can be fully effective within a short time. The flange preferably forms a metallic seal.
Depending on the geometry of the seal, it may, under certain circumstances, be expedient to provide the flange with at least one sealing element, with the result that the costs of producing the flange can be reduced, since there is no need to accurately form sealing surfaces on the flange.
According to a further advantageous embodiment of the catalyst carrier configuration, the catalyst carrier body is a metallic catalyst carrier body, preferably a monolithic honeycomb body. Using a metallic catalyst carrier body has the advantage that the catalyst carrier body can be soldered at least to the housing and/or the flange, so that an increased stability of the catalyst carrier configuration is achieved.
The metallic catalyst carrier body may include layers of metal sheet which are at least partially structured. As an alternative, the catalyst carrier body may be produced from a sintered metal.
As an alternative to a metallic catalyst carrier body, it is also possible to use a ceramic catalyst carrier body. In this case, however, it should be ensured that the different thermal expansions caused by different coefficients of expansions of the materials of the catalyst carrier body and of the housing, which is metallic, are compensated for by suitable measures.
According to a further advantageous embodiment of the catalyst carrier configuration, the catalyst carrier body has at least one region which has at least one passage which has a larger cross section than the further passages. This measure ensures that the flow behavior of the exhaust-gas stream is not affected, or is affected only to a very slight extent, by the catalyst carrier body. Such an effect is important in particular if it has a feedback effect on the mixture formation within a combustion chamber of an internal combustion engine.
With the objects of the invention in view there is also provided, a structural unit, including:
at least two catalyst carrier configurations, each including a housing having an outer wall and a catalyst carrier body disposed in the housing, the catalyst carrier body defining an axial direction and having partition walls defining a plurality of passages separated from one another by the partition walls and extending essentially in the axial direction; and
a common flange surrounding the catalyst carrier body of each of the at least two catalyst carrier configurations and extending essentially radially outwards, the common flange having at least one section extending at least partially into the outer wall of each of the at least two catalyst carrier configurations and being configured to be disposed between a cylinder head and a manifold of an internal combustion engine.
The number of catalyst carrier configurations preferably corresponds to the number of outlet passages from an internal combustion engine. As a result, it is possible to reduce the assembly outlay on the catalyst carrier configurations. In particular in the case of a structural unit in which the number of catalyst carrier configurations corresponds to the number of outlet passages of an internal combustion engine, it is possible, given a suitable configuration of the internal combustion engine and an appropriately configured structural unit, to connect this structural unit directly to the internal combustion engine, so that part of each catalyst carrier body projects into an outlet passage of the internal combustion engine.
Preferably, such a structural unit is configured in such a way that each catalyst support is disposed inside a sealing surface. As an alternative, appropriate seals may be formed on the joint or common collar for each catalyst support.
With the objects of the invention in view there is also provided, an exhaust system for an internal combustion engine, including:
an exhaust system component defining at least one exhaust flow path; and
a catalyst carrier configuration including a housing having an outer wall, at least one catalyst carrier body disposed in the housing and provided at least partly in the at least one exhaust flow path, the at least one catalyst carrier body defining an axial direction and having partition walls defining a plurality of passages separated from one another by the partition walls and extending essentially in the axial direction, and a at least one flange surrounding at least the at least one catalyst carrier body and extending essentially radially outwards from the at least one catalyst carrier body, the at least one flange having at least one section extending at least partially into the outer wall and being configured to be disposed between a cylinder head and a manifold of an internal combustion engine.
With the objects of the invention in view there is further provided, an exhaust system for an internal combustion engine, including:
an exhaust system component defining exhaust flow paths; and
a structural unit including at least two catalyst carrier configurations, each including a housing having an outer wall and a catalyst carrier body disposed in the housing and provided at least partly in a respective one of the exhaust flow paths, the catalyst carrier body defining an axial direction and having partition walls defining a plurality of passages separated from one another by the partition walls and extending essentially in the axial direction, and a common flange surrounding the catalyst carrier body of each of the at least two catalyst carrier configurations and extending essentially radially outwards, the common flange having at least one section extending at least partially into the outer wall of each of the at least two catalyst carrier configurations and being configured to be disposed between a cylinder head and a manifold of an internal combustion engine.
The exhaust systems according to the invention make it possible to install catalyst carrier bodies in the immediate vicinity of an internal combustion engine.
Preferably, one catalyst carrier body is in each case disposed in each flow path, making it possible to reduce the emission of harmful components in the exhaust gas. In order to make the exhaust system as effective as possible and to avoid bypass flows of an exhaust gas, each catalyst carrier body with a housing has a cross section which essentially corresponds to a cross section of an exhaust-gas flow path.
According to a further advantageous embodiment of the exhaust system having at least one manifold which has at least one flange for connection to an internal combustion engine, the collar bears at least partially against the flange. In particular, the collar is configured in such a way that it can be connected to the flange in a gastight manner. Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a catalyst carrier configuration for installation close to the engine, a structural unit having catalyst carrier configurations and an exhaust system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.